JP2021108476A - Radio station, radio terminal, and method therefor - Google Patents

Abstract

To help acquire information useful for a radio station to determine whether to allow a radio terminal to perform communication on an unlicensed frequency.SOLUTION: A radio station (1) operates a first cell on a licensed frequency and functions as a master node when a radio terminal (3) performs Dual Connectivity. The radio station (1) transmits, to the radio terminal (3) in the first cell, a measurement setting including control information associated with a reference signal measurement in a cell operated on a common frequency. The control information includes information indicating the periodicity with which a first period, during which the reference signal measurement is performed, occurs and an offset value for indicating a subframe number where the first period starts. The radio station (1) receives the result of the reference signal measurement performed during the first period according to the offset value and the information indicating the periodicity from the radio terminal (3) in the first cell.SELECTED DRAWING: Figure 3

Description

The present application relates to a radio communication system in which a radio station communicates with a radio terminal on an unlicensed frequency or a shared frequency.

In order to improve the deterioration of communication quality due to the rapid increase in mobile traffic in recent years and to realize higher-speed communication, 3GPP Long Term Evolution (LTE) uses wireless base stations (eNode B: eNB) and wireless terminals (User Equipment: UE). ) Has specified the Carrier Aggregation (CA) function that communicates using multiple cells. The cells that the UE can use in the CA are limited to a plurality of cells of one eNB (that is, a plurality of cells operated or managed by the eNB). The cells used by the UE in the CA are the primary cell (PCell) that is already used as a serving cell at the time of starting the CA, and the secondary cell (SCell) that is additionally or subordinately used. are categorized. At PCell, Non Access Stratum (NAS) mobility information and security input during Radio Resource Control (RRC) Connection Establishment, RRC Connection Re-establishment. Is transmitted and received (see Section 7.5 of Non-Patent Document 1).

On the other hand, the introduction of CA has made it possible to realize high-speed communication functionally, but in actual operation, due to the limitation (insufficiency) of the frequency assigned to each operator, it is possible to cope with the further increase in mobile traffic in the future. The current situation is that there are concerns. Therefore, in 3GPP standardization, there is a discussion of Unlicensed LTE (also called LTE-U or U-LTE, hereinafter referred to as LTE-U) that executes LTE using unlicensed frequency band (Unlicensed spectrum). It has been started (Non-Patent Documents 2 and 3).

LTE-U implementation methods include Licensed Assisted Access (LAA), in which the eNB communicates with the UE at an unlicensed frequency in conjunction with the licensed frequency (for example, as a CA SCell), and communication with the UE only at an unlicensed frequency. There are two possible methods of Standalone (SA). Here, as the unlicensed frequency, for example, the 5 GHz band is assumed, and the 5 GHz band is also a frequency used for a radar system and a wireless LAN (Wireless LAN: WLAN, also referred to as WiFi). Therefore, there is concern about the feasibility of fine control specified by LTE for the SA method that communicates only on unlicensed frequencies, and the LAA method (also called LA-LTE), which has a relatively high feasibility, is being considered. It is considered to be the center of. In the following, we will focus on LTE-U using the LAA method, which performs CA on licensed and non-licensed frequencies. The license frequency refers to a dedicated frequency assigned to a specific operator. The non-licensing frequency refers to a frequency that is not assigned to a specific operator or a shared frequency that is assigned to a plurality of operators. In the latter case, the frequency is sometimes referred to as a licensed shared frequency instead of being referred to as an unlicensed frequency, and communication using that frequency is also referred to as Licensed Shared Access (LSA). Hereinafter, these frequencies other than the licensed frequencies licensed only to a specific operator are collectively referred to as non-licensed frequencies.

LTE-U by the LAA method is basically executed according to the sequence shown in FIG. Here, it is assumed that the eNB transmits (or receives) data between the licensed frequency Cell # 1 and the non-licensed frequency Cell # 2 and the UE # 1. First, in Cell # 1, a wireless connection is established between eNB and UE # 1 (RRC Connection Establishment, S901), and then a bearer is established between the core network (Evolved Packet Core: EPC) and UE # 1 (RRC Connection Establishment, S901). Not shown). In other words, Cell # 1 becomes the PCell of UE # 1. eNB has downlink (DL) / user data (also called User Plane (UP) data) that should be transmitted to UE # 1, or uplink (UL) / user data that UE # 1 wants to transmit. , The user data is transmitted / received in Cell # 1 (DL (or UL) UP data transmission, S902).

Next, if the eNB determines that it is effective for UE # 1 to send and receive user data in Cell # 2 at some point (Trigger LTE-U for UE # 1, S903), Cell # 1 in Cell # 1. Send control information about the radio resource configuration of 2 to UE # 1 (Radio Resource Configuration for Cell # 2, S904). The control information corresponds to RadioResourceConfigDedicated Information Element (IE) and RadioResourceConfigCommon IE transmitted by RRC Connection Reconfiguration message in LTE (Non-Patent Document 4). At this time, Cell # 2 becomes the SCell of UE # 1. When transmitting user data via a downlink, eNB performs sensing in Cell # 2 and determines whether the Cell # 2 is available (Perform channel sensing, S905). When eNB determines that Cell # 2 is available, it sends and receives user data to and from UE # 1 (DL (or UL) UP data transmission, S906). In this way, the use of unlicensed frequencies can be expected to further improve throughput or increase cell capacity.

The above-mentioned sensing is also called Listen Before Talk (LBT) (Non-Patent Document 2), and communication by LTE-U or another wireless system (eg WLAN) by another operator at the target non-licensed frequency is performed. It determines whether or not it is performed in the neighborhood, and corresponds to the Channel Availability Check (CAC) for the radar system and the Clear Channel Assessment (CCA) performed at the Access Point (AP) on the WLAN (Patent Document 1). ).

3GPP TS 36.300 V12.2.0 (2014-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description Stage 2 (Release 12) ”, June 2014 3GPP RP-131635, “Introducing LTE in Unlicensed Spectrum”, Qualcomm, Ericsson, December 2013 3GPP workshop on LTE in unlicensed spectrum, RWS-140002, “LTE in Unlicensed Spectrum: European Regulation and Co-existence Considerations”, Nokia, June 2014 3GPP TS 36.331 V12.2.0 (2014-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification (Release 12)” , June 2014 3GPP TR 36.842 V12.0.0 (2013-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on Small Cell enhancements for E-UTRA and E-UTRAN; Higher layer aspects (Release 12)”, 2013 December

U.S. Pat. No. 7,443,821

In the background technology described above, the base station (eNB) determines whether or not to allow the UE to communicate in the unlicensed frequency cell (Cell # 2) based on the measurement report by UE. It is expected to judge. For example, the eNB instructs the UE to report the terminal measurement in the cell of the license frequency (Cell # 1), the UE executes the terminal measurement in the cell of the non-licensed frequency (Cell # 2, etc.), and the UE performs the terminal measurement. Report the result of the terminal measurement in Cell # 1. The eNB determines whether or not it is appropriate to transmit the user data in Cell # 2 to the UE based on the result of the terminal measurement in Cell # 2. For example, the eNB may determine whether or not the reception quality (RSRP or RSRQ) of the reference signal (RS) in the unlicensed frequency cell (Cell # 2, etc.) is equal to or higher than a predetermined value. Then, when the eNB determines that it is appropriate, the user data is transmitted in Cell # 2 to the UE (for example, UE # 1 of the background technology).

However, when using terminal measurement reports in regular LTE, it may not be possible to allow appropriate UEs to communicate at (cells in) unlicensed frequencies. This is because the unlicensed frequency is shared with other wireless systems as described above, so the reference signal is not always transmitted as in the LTE cell. For example, the UE calculates the value in the terminal measurement report by averaging the reception quality while the reference signal is being transmitted from another wireless system and the reception quality while it is not being transmitted (which is an invalid value in this case). May do. Then, the reception quality at the non-licensed frequency shown in the terminal measurement report may be calculated to be lower than the threshold level set for determining that it is appropriate to perform communication at the non-licensed frequency (cell). be. In such a case, even if it is determined that the unlicensed frequency can be used based on the above-mentioned sensing by eNB (S905 in FIG. 15), the use of the unlicensed frequency cannot be permitted to the appropriate UE. The performance improvement (eg throughput improvement or cell capacity increase) by using the licensed frequency may not be sufficiently obtained.

Therefore, one of the objectives to be achieved by the embodiments disclosed herein is to allow radio stations (eg UEs) to communicate at (cells) in non-licensing frequencies. To provide devices, methods, and programs that contribute to the acquisition of useful information for accurate determination in eNB).

In the first aspect, the methods performed at the radio station are: (a) communicating with the radio terminal at a licensed frequency, (b) control associated with at least one of the measurement timing and the measurement period of the terminal measurement at a non-licensed frequency. The signaling is transmitted to the radio terminal at the license frequency, and (c) the result of the terminal measurement performed according to at least one of the measurement timing and the measurement period in response to the control signaling is obtained at the license frequency. Including receiving from the wireless terminal.

In the second aspect, the radio station includes a radio communication unit (transceiver) and a control unit (controller). The wireless communication unit is configured to communicate at licensed and non-licensed frequencies. The control unit transmits the control signaling associated with at least one of the measurement timing and the measurement period of the terminal measurement at the non-licensed frequency to the wireless terminal at the licensed frequency, and in response to the control signaling, the measurement timing and the said. The result of the terminal measurement performed according to at least one of the measurement periods is configured to be received from the wireless terminal at the licensed frequency.

In a third aspect, the methods performed on the wireless terminal are: (a) communicating with the radio station at a licensed frequency, (b) control associated with at least one of the measurement timing and measurement period of the terminal measurement at a non-licensed frequency. The signaling is received from the radio station at the licensed frequency, (c) the terminal measurement is performed in response to the control signaling according to at least one of the measurement timing and the measurement period, and (d) the terminal measurement. The result of the above is transmitted to the radio station at the licensed frequency.

In the fourth aspect, the wireless terminal includes a wireless communication unit (transceiver) and a control unit (controller). The radio communication unit is configured to communicate with a radio station at licensed and non-licensed frequencies. The control unit receives the control signaling associated with at least one of the measurement timing and the measurement period of the terminal measurement at the non-licensed frequency from the radio station at the licensed frequency, and in response to the control signaling, the measurement timing and The terminal measurement is performed according to at least one of the measurement periods, and the result of the terminal measurement is transmitted to the radio station at the license frequency.

In the fifth aspect, the program includes an instruction group (software code) for causing the computer to perform the method according to the first aspect described above when read by the computer.

In the sixth aspect, the program includes an instruction group (software code) for causing the computer to perform the method according to the third aspect described above when read by the computer.

In a seventh aspect, the method for terminal measurement is (a) transmitting control signaling associated with at least one of the measurement timing and measurement period of the terminal measurement at the unlicensed frequency from the radio station to the radio terminal at the licensed frequency. To perform the terminal measurement by the wireless terminal according to at least one of the measurement timing and the measurement period in response to the control signaling, and (c) the result of the terminal measurement is the licensed frequency. The above includes transmitting from the radio terminal to the radio station.

According to the above aspect, it is necessary to acquire useful information for the radio station (eg eNB) to determine whether or not to allow the radio terminal (eg UE) to communicate at (cell) of the non-licensed frequency. Contribution devices, methods, and programs can be provided.

It is a figure which shows the configuration example of the wireless communication system and other wireless systems which concerns on some Embodiments. It is a figure which shows the configuration example of the wireless communication system and other wireless systems which concerns on some Embodiments. It is a figure which shows the configuration example of the wireless communication system and other wireless systems which concerns on some Embodiments. It is a sequence diagram which shows an example of the operation of the wireless base station and the wireless terminal which concerns on 1st Embodiment. It is a sequence diagram which shows an example of the operation of the wireless base station and the wireless terminal which concerns on 1st Embodiment (specific example 1). It is a figure which shows an example of the terminal measurement by the wireless terminal which concerns on 1st Embodiment (specific example 2). It is a figure which shows an example of the terminal measurement by the wireless terminal which concerns on 1st Embodiment (specific example 3). It is a figure which shows an example of the terminal measurement by the wireless terminal which concerns on 1st Embodiment (specific example 4). It is a sequence diagram which shows an example of the operation of the wireless base station and the wireless terminal which concerns on 2nd Embodiment. It is a figure which shows the configuration example of the wireless communication system and other wireless systems which concerns on some Embodiments. It is a sequence diagram which shows an example of the operation of two radio base stations and a radio terminal which concerns on 3rd Embodiment. It is a sequence diagram which shows the example of the operation of two radio base stations (MeNB and SeNB) which concerns on 3rd Embodiment (specific example 5). It is a sequence diagram which shows the example of the operation of two radio base stations (MeNB and SeNB) which concerns on 3rd Embodiment (specific example 6). It is a block diagram which shows the structural example of the radio base station which concerns on some Embodiments. It is a block diagram which shows the structural example of the wireless terminal which concerns on some Embodiments. It is a sequence diagram which shows an example of the operation of a wireless base station and a wireless terminal in LTE-U.

Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary for the sake of clarity of explanation.

The plurality of embodiments shown below are described mainly for Evolved Packet System (EPS) accommodating LTE and SAE (System Architecture Evolution). However, these embodiments are not limited to EPS, but other mobile communication networks or systems such as 3GPP Universal Mobile Telecommunications System (UMTS), 3GPP2 CDMA2000 System (1xRTT, HRPD (High Rate Packet Data)), It may be applied to global system for mobile communications (GSM®) / General packet radio service (GPRS) system, WiMAX system and the like.

<First Embodiment>
First, some examples of Unlicensed LTE utilizing the unlicensed frequency band (Unlicensed spectrum) targeted by a plurality of embodiments including the present embodiment will be described. Here, Unlicensed LTE is also referred to as LTE-U or U-LTE, and will be described hereinafter as LTE-U. The non-licensed frequency is a frequency that is also used for radar systems and wireless LANs (WLAN, also called WiFi), and is a frequency other than the licensed frequency assigned only to a specific operator (that is, a service provider). Point to. The unlicensed frequency is assumed to be, for example, the 5 GHz band, but is not limited to this. Further, it goes without saying that the plurality of embodiments described below are also applicable to a shared frequency band (shared spectrum) commonly assigned to a plurality of operators. Hereinafter, these frequencies other than the licensed frequencies are collectively referred to as non-licensed frequencies.

1A, 1B, and 2 are diagrams showing configuration examples of an LTE-U wireless communication system and other systems targeted by a plurality of embodiments including the present embodiment. In the example of FIG. 1A, the radio communication system includes an LTE radio base station (eNB) 11 and a radio terminal (UE) 3. The eNB 11 and UE3 are configured to perform normal LTE communication at the licensed frequency (F1), and are configured to perform LTE-U communication at the non-licensed frequency (F2). On the other hand, the unlicensed frequency (F2) is also used for communication between the wireless LAN access point (WLAN AP) 4 and the wireless LAN terminal (WLAN Terminal) 5. In the example of FIG. 1B, in addition to the example of FIG. 1A, the LTE eNB 11 manages the remote base station 12 (RRH or RRE), and the remote base station 12 communicates by LTE-U at an unlicensed frequency (F2). ..

The configurations of FIGS. 1A and 1B may coexist in the same system. Further, FIGS. 1A and 1B show only a part of the assumed wireless communication system, and in reality, there are a plurality of eNBs and RRH / RREs and a plurality of UEs around the eNB 11, RRH / RRE12, and UE3. , Multiple licensed frequency cells are managed by these multiple eNBs and RRH / RRE. Further, there may be a plurality of WLAN APs and WLAN Terminals around the eNB 11, RRH / RRE 12, and UE 3. In the following description, eNBs having LTE-U functions are collectively referred to as radio base station 1 or LTE-U eNB1. That is, the radio base station 1 or LTE-U eNB 1 corresponds to eNB 11 in the configuration of FIG. 1A, and corresponds to eNB 11 and RRH / RRE 12 in the configuration of FIG. 1B. For convenience of explanation, only the node corresponding to RRH / RRE12 in the configuration of FIG. 1B may be referred to as radio base station 1 or LTE-U eNB1.

FIG. 2 is a configuration example of the LTE-U wireless communication system and other wireless communication systems when focusing on unlicensed frequencies. A wireless base station (LTE-U eNB-A) 1A having the LTE-U function of an operator (service provider) A and a wireless terminal (UE for Operator A. UE-A) that can be connected to the network of the operator A. There is 3A. Similarly, a radio base station (LTE-U eNB-B) 1B having the LTE-U function of another operator (service provider) B and a wireless terminal (UE for Operator B.) that can be connected to the network of the operator B. UE-B) 3A exists. Here, LTE-U eNB1A and 1B correspond to, for example, eNB11 and RRH / RRE12 in FIGS. 1A and 1B, and are also called LTE-U APs in the sense of LTE-U access points. Further, similarly to FIGS. 1A and 1B, there are WLAN AP4 and WLAN Terminal 5 around LTE-U eNB1A and 1B and UE3A and 3B.

In the above and subsequent description, it is assumed that LTE-U is realized by LAA (also called LA-LTE). As already mentioned, in LAA, the radio base station (LTE-U eNB) 1 and the radio terminal (UE) 3 carry out carrier aggregation (CA) of the licensed frequency cell and the non-licensed frequency cell, and the licensed frequency cell. Is used as the primary cell (PCell), and the cell with the unlicensed frequency is used as the secondary cell (SCell). As already mentioned, LTE-U may be executed on a shared frequency band (Shared spectrum) assigned to a plurality of operators (service providers) instead of being executed on an unlicensed frequency. In this case, LTE-U may be realized by the above-mentioned LAA or a similar method. Alternatively, LTE-U eNB1 and UE3 perform CA using multiple shared frequencies (for example, F3 and F4), and perform normal LTE with one shared frequency (F3) as PCell. LTE-U may be executed with one shared frequency (F4) as the SCell. As already mentioned, LTE-U at shared frequencies is also called Licensed Shared Access (LSA) in particular. Furthermore, LTE-U eNB1 and UE3 use a shared frequency assigned to multiple operators (eg F3) and a narrowly defined unlicensed frequency not assigned to any operator (eg F2, eg 5GHz band). Then, CA may be performed, and normal LTE may be executed with the shared frequency (F3) as PCell, and LTE-U may be executed with the unlicensed frequency (F2) in the narrow sense as SCell.

Further, in a plurality of embodiments including the present embodiment, for simplification of explanation, communication at an unlicensed frequency (or shared frequency) executed by LTE-U is basically wireless from the radio base station 1. It is assumed that downlink data is transmitted to the terminal 3. However, it goes without saying that communication at an unlicensed frequency (or shared frequency) in LTE-U can also be applied to uplink data transmission from the wireless terminal 3 to the wireless base station 1. Further, when communication between the radio base station 1 and the radio terminal 3 at the non-licensed frequency is possible only for downlink, the non-licensed frequency is substantially in LAA using the non-licensed frequency as a secondary cell (SCell). It does not have a role as a single cell, but only as a downlink secondary carrier (SCC). However, in the description of the embodiment including the present embodiment, basically, whether or not the non-licensed frequency has a role as a cell by itself is explained without distinction, and a supplementary explanation is given as necessary. do.

FIG. 3 is a sequence diagram showing the operation of the radio base station (LTE-U eNB) 1 and the radio terminal (UE) 3 in the first embodiment. The wireless terminal 3 is displayed as UE # 1 in FIG. In FIG. 3, it is assumed that LTE-U eNB1 manages a cell (Cell # 1) at a licensed frequency (F1) and a cell (Cell # 2) at a non-licensed frequency (F2).

In FIG. 3, UE3 first establishes a wireless connection with LTE-U eNB1 in Cell # 1 (RRC Connection Establishment, S101), and further establishes a bearer (eg EPS bearer, E-) with a core network (EPC) (not shown). RAB) is established. After that, for example, user data can be transmitted and received (not shown). LTE-U eNB1 instructs UE3 to measure a terminal at an unlicensed frequency (for example, F2) by a predetermined control signaling in Cell # 1 (Measurement Configuration and Instruction for Unlicensed Frequency (eg Cell # 2 on). F2), S102). In other words, the predetermined control signaling transmitted by Cell # 1 indicates an indication of UE measurement at an unlicensed frequency (eg, F2), either explicitly or implicitly.

The control signaling or terminal measurement instruction (S102) indicates when the UE3 should measure the terminal measurement at the Unlicensed Frequency (for example, Cell # 2 of F2) (that is, the terminal measurement should be performed). It is associated with at least one of the timing and the measurement period, which indicates when to measure (ie, it is reasonable to perform a terminal measurement). In other words, the control signaling or terminal measurement instruction (S102) explicitly indicates at least one of the measurement timing and measurement period (measurable period) of the terminal measurement at the Unlicensed Frequency (for example, Cell # 2 of F2) by UE3. Show or implied. For example, the terminal measurement instruction may explicitly indicate at least one of the measurement timing and the measurement period, or may include information regarding at least one of the measurement timing and the measurement period. In addition, the terminal measurement instruction may include information about a cell of a non-licensed frequency and / or a non-licensed frequency that is the target of terminal measurement, or both. Further, the number of unlicensed frequencies to be measured by the terminal may be one or a plurality as shown in FIG. Similarly, the number of cells with unlicensed frequencies may be one or plural. Note that the setting information (Measurement Configuration: MeasConfig) for terminal measurement and the terminal measurement instruction (Measurement Instruction) may be transmitted by the same control signaling, or separate control signaling (or control message and control signaling). May be sent by.

Here, the setting information (MeasConfig) for terminal measurement includes, for example, at least one of information on one or more non-license frequencies of interest and information on cells at the non-licensed frequency. Information on unlicensed frequencies may be presented, for example, in any or combination of the following:
・ LTE frequency identifier (eg E-UTRA Absolute Radio Frequency Channel Number (EARFCN));
-Unlicensed frequency index, and- (center) frequency (eg carrier frequency).
The unlicensed frequency identifier may be defined by adding a new number or index to the unlicensed frequency that can be used in LTE-U.

Cell information at unlicensed frequencies may be presented, for example, in any or combination of the following:
• Cell identifier (eg Physical Cell Identifier (PCI), EUTRAN Cell Global ID (ECGI), or Virtual Cell ID), and • Unlicensed Cell Identifier (eg Unlicensed Cell ID).
The Virtual Cell ID may be, for example, a scrambling code identifier (eg Scrambling Identity or Scrambling Code ID) used for transmitting a reference signal in the cell of the non-licensed frequency. Further, the non-licensed frequency cell identifier may be defined by newly assigning a cell number or a cell index to the cell of the non-licensed frequency.

Furthermore, MeasConfig may include other network identifiers (e.g. Public Land Mobile Network Identifier (PLMN ID), Tracking Area Identity (TAI), or Tracking Area Code (TAC)). When MeasConfig includes these network identifiers, the wireless terminal 3 may perform the terminal measurement in the cell in response to the confirmation of the specified network identifier in the cell to be measured by the terminal.

In addition, MeasConfig may include information about other systems at unlicensed frequencies for terminal measurement. Information about other systems may be, for example, a WLAN (Access Point) identifier (e.g. Service Set Identifier (SSID), Basic SSID (BSSID), or Homogenous Extended SSID (HESSID)). When MeasConfig includes a WLAN identifier, the wireless terminal 3 responds by detecting the specified WLAN identifier at an unlicensed frequency to be measured by the terminal, and receives the signal reception quality (eg Received Signal) of the WLAN. The Strength Indicator (RSSI), Received Channel Power Indicator (RCPI), or Received Signal to Noise Indicator (RSNI)) may be measured and reported to Radio Base Station 1.

The explanation will be continued by returning to FIG. UE3 responds to the control signaling (S102), that is, follows the terminal measurement instruction, performs terminal measurement in Cell # 2 (Measurement, S104), and obtains the result of the terminal measurement in Cell # 1 LTE-U eNB. (Measurement Reporting for Unlicensed Frequency (eg Cell # 2 on F2), S105). UE3 may measure the reception strength or reception quality of the reference signal (S103) transmitted from LTE-U eNB1 in Cell # 2 in the terminal measurement (S104), for example. The terminal measurement and the terminal measurement report may be performed not only on the cell (Cell # 2) of the non-licensed frequency (F2) but also on another cell of F2, another unlicensed frequency, or a licensed frequency. Here, the terminal measurement instruction may be explicitly given, or the transmission of the above-mentioned information regarding the terminal measurement timing or measurement period may be an implicit terminal measurement instruction.

In this way, the radio base station (LTE-U eNB) 1 designates (instructs) the radio terminal (UE) 3 for the measurement timing and / or measurement period of the terminal measurement in the terminal measurement at the non-licensed frequency. , Expected terminal measurement results can be collected. Then, whether or not the LTE-U eNB1 can communicate with the UE3 (that is, data transmission / reception by LTE) at the non-licensed frequency (cell) based on the terminal measurement result (or is appropriate). Can be determined.

However, the radio base station (LTE-U eNB) 1 is not always capable of operating LTE at (cells) of unlicensed frequencies. The LTE-U eNB1 appropriately confirms whether or not the unlicensed frequency can be used for LTE-U by sensing or the like, and if it can be used, for example, a synchronization signal (Synchronization Signal) and a reference signal (Reference). Signal) may be sent. Therefore, the LTE-U eNB1 transmits the control signaling so that the measurement timing or the measurement period of the terminal measurement at the non-licensed frequency falls within the period during which the unlicensed frequency can be used (that is, the available period). Alternatively, the control information carried by the control signaling (indicating at least one of the measurement timing and the measurement period) may be adjusted. In one example, LTE-U eNB1 may specify the measurement timing and / or measurement period so that they are within the period in which the unlicensed frequencies are determined to be available. Further, when it is determined that the non-licensed frequency is available, or while the non-licensed frequency is available, LTE-U eNB1 gives an instruction for terminal measurement at the non-licensed frequency by predetermined control signaling. You may send it. As already mentioned, the above-mentioned sensing by LTE-U eNB1 is also called Listen Before Talk (LBT). The sensing corresponds to, for example, a CAC for a radar system or a CCA performed on a WLAN AP. Here, CAC may not be performed if the target unlicensed frequency is not the frequency used in the radar system.

<< Specific example 1 >>
A specific example 1 in the first embodiment will be described. FIG. 4 is a sequence diagram showing the operations of the radio base station (LTE-U eNB) 1 and the radio terminal 3 in the first embodiment. The assumption of FIG. 4 is the same as that of FIG. 3, and the radio base station (LTE-U eNB) 1 has a cell (Cell # 1) at the licensed frequency (F1) and a cell (Cell # 2) at the unlicensed frequency (F2). To manage. LTE-U eNB1 instructs UE3 to measure a terminal at a non-licensed frequency (F2), and based on the result of the terminal measurement, performs LTE-U communication (for example, downlink data transmission) with UE3 at the non-licensed frequency. Decide whether to do it or not. The wireless terminal 3 is displayed as UE # 1 in FIG.

In FIG. 4, UE3 first establishes a wireless connection with LTE-U eNB1 in Cell # 1 (RRC Connection Establishment, S201), and further establishes a bearer (eg EPS bearer, E-) with a core network (EPC) (not shown). RAB) is established. After that, for example, in Cell # 1, user data can be transmitted and received (not shown). The LTE-U eNB1 performs the first sensing at the unlicensed frequency (F2) (Perform first channel sensing, S202). Here, the first sensing includes CAC for a radar system, CCA for another system such as WLAN, CCA for LTE-U by another operator (service provider), or two or all of them. When the LTE-U eNB1 determines that the unlicensed frequency (F2) can be used by the first sensing (S202), the terminal in F2 (cell (Cell # 2)) is sent to UE3 by a predetermined control signaling. Upon instructing the measurement, UE3 performs the terminal measurement according to the instruction and reports the result of the terminal measurement to LTE-U eNB1 (Measurement Configuration, Instruction and Reporting for Unlicensed Frequency, S203). Based on the reported terminal measurement result, LTE-U eNB1 determines whether or not to perform communication with UE3 in Cell # 2 (for example, downlink data transmission) (S204).

Here, the terminal measurement is, for example, the reception quality of the reference signal (RS) (Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), RSSI, Channel Quality Indicator (CQI), or Signal-to-Interference. -plus-Noise ratio (SINR)) measurements may be included. Then, the determination by LTE-U eNB1 may be performed based on whether or not the reported reception quality value is equal to or greater than a predetermined value (or larger than a predetermined value). The reference signal is a general term for signals whose types and sequences of signals or their candidates are known in advance in the wireless terminal 3, and is also called a pilot signal. The reference signal in LTE is, for example, Cell Specific Reference Signal (CRS), which is different for each cell, CSI (Channel State Information) RS, which is also used for CQI measurement, or DRS (Discovery Reference Signal), which is used for cell detection. include.

Further or instead, the terminal measurement receives a predetermined signal specified by another system such as WLAN (eg, a reference signal, or all or part of a signal transmitted at the frequency of the system). Quality (RSSI, RCPI, or RSNI) measurements may be included. At this time, the determination by LTE-U eNB1 may be performed depending on whether or not the reported reception quality value is equal to or less than a predetermined value (or less than a predetermined value). Alternatively, the UE 3 may detect the signal of another system such as WLAN in the terminal measurement (that is, try to detect it) and report the result of the detection. At this time, the determination by LTE-U eNB1 may be made in consideration of whether or not it is reported that another system has been detected.

Further or instead, the UE 3 may acquire load information (BSS (Basic Service Set) Load) of another system such as WLAN in terminal measurement and report the load information. At this time, the determination by LTE-U eNB1 may be performed in consideration of whether or not the load of the other system is equal to or greater than a predetermined threshold value (greater than the threshold value). Based on the results of the plurality of terminal measurements described above, the LTE-U eNB 1 may make the determination as to whether or not to perform communication with the UE 3 in Cell # 2.

When LTE-U eNB1 determines that Cell # 2 communicates with UE3, it transmits the radio resource setting information (Radio Resource Configuration, eg RadioResourceConfigCommon and RadioResourceConfigDedicated) of Cell # 2 to UE3 in Cell # 1 (Cell # 1). Radio Resource Configuration for Cell # 2, S205). At this time, LTE-U eNB1 may use, for example, an RRC Connection Reconfiguration message.

Then, LTE-U eNB1 performs a second sensing at an unlicensed frequency (F2) (Perform second channel sensing, S206). The second sensing may be the same as or different from the first sensing. When the LTE-U eNB1 determines that the unlicensed frequency (F2) can be used, it transmits user data (UP data) to UE3 in Cell # 2 (S207). At this time, the scheduling of the user data (that is, the notification of the radio resource allocation information) may be performed in the cell (eg Cell # 1) of the license frequency (eg F1) or in Cell # 2. good. For the former scheduling, a technique called cross-carrier scheduling may be used in LTE. In addition, the transmission of user data to UE3 in Cell # 2 is based on the CSI feedback information (eg CQI, Precoding Matrix Indicator (PMI), Rank Indicator (RI)) for Cell # 2 reported from UE3 in Cell # 1. May be done in.

By the above procedure, the radio base station (LTE-U eNB) 1 can appropriately determine the radio terminal (UE) 3 to which LTE (LTE-U) at an unlicensed frequency is permitted. As a result, improvement of the overall characteristics of the LTE wireless communication system, for example, system throughput can be expected.

<< Specific example 2 >>
Specific Example 2 in the first embodiment will be described. The difference from the specific example 1 is that the radio base station (LTE-U eNB) 1 uses the control signaling generated by using the control information specified for the instruction of the terminal measurement at the unlicensed frequency. .. The control signaling may explicitly include the control information, or the control information may be used for data scrambling in the process of generating the control signaling. In Specific Example 2, a Layer 1 (L1) control signal or a Layer 1 (L1) control signal transmitted on a downlink physical control channel (PDCCH) is used as a control signaling for transmitting a terminal measurement instruction at an unlicensed frequency (F2). 2 (L2) Control signals or both (L1 / L2 signaling) are used. The control information is U-RNTI (LTE-U RNTI, U-LTE RNTI, or Unlicensed RNTI), which is a type of identifier (Radio Network Temporary Identifier: RNTI) used for generating and detecting PDCCH. The U-RNTI has a common value for a plurality of wireless terminals 3 (that is, wireless terminals having the ability to communicate at a non-licensed frequency) that are in a wireless connection state (RRC_CONNECTED) in the cell of the license frequency (eg F1). It may be set.

That is, the control signaling (L1 / L2 control signal) that transmits the terminal measurement instruction at the unlicensed frequency (F2) uses the U-RNTI (that is, the Cyclic Redundancy Check (CRC) part is performed by the U-RNTI. (Scramble (d)) and sent. In one example, a new PDCCH format (Downlink Control Information (DCI) format) may be specified for terminal measurement instructions at unlicensed frequencies. Instead, LTE-U PDCCH (U-PDCCH) may be specified as a new physical control channel, and the U-PDCCH may be used to transmit L1 / L2 control signals instead of PDCCH. The U-PDCCH may be specified to use, for example, a portion of the area of the Physical Downlink Shared Data Channel (PDSCH).

In the second embodiment, the fact that the wireless terminal (UE3) receives the control signaling implicitly indicates the measurement timing. That is, when the wireless terminal (UE) 3 receives the control signaling, it recognizes that it has been instructed to perform terminal measurement in the cell (Cell # 2) of the unlicensed frequency (F2). In order to realize this, the radio base station (LTE-U eNB) 1 previously provides the setting information (for example, Measurement Configuration: MeasConfig) required for terminal measurement for the cell (Cell # 2) of the unlicensed frequency (F2) in RRC. It suffices to notify the wireless terminal (UE) 3 in the cell (Cell # 1) of the license frequency (F1) by signaling.

Here, MeasConfig is, for example, information (eg EARFCN, Unlicensed frequency index, or carrier frequency) of one or more target non-licensed frequencies (F2), and a cell (Cell) at the non-licensed frequency (F2). # 2) Contains at least one of the information (eg PCI, ECGI, Virtual Cell ID, Unlicensed Cell ID). In addition, the radio base station (LTE-U eNB) 1 uses MeasConfig or other RRC information elements (IE) to provide the radio terminal (UE) with information about the allottable period of unlicensed frequencies to LTE-U. You may notify. Information about the allocatable period is the Duty Cycle Period (in eg ms units), which corresponds to the reference period for defining the allocatable period, and the Duty Cycle (eg% unit), which corresponds to the percentage of the allocatable period in the reference period. Either or both of the above may be included. For example, if the duty cycle period is 200 ms and the duty cycle is 50%, then LTE-U can be considered to have an allocatable period of 100 ms every 200 ms. The values of the Duty Cycle Period and the Duty Cycle may be specified in advance in the specifications, for example, or from the control device (eg Mobility Management Entity (MME) or Operation, Administration and Maintenance (OAM) entitiy) to the radio base station. It may be sent to 1. Alternatively, the radio base station 1 itself may appropriately determine the duty cycle period and the duty cycle based on the sensing result and the like.

FIG. 5 is a diagram for explaining terminal measurement by the wireless terminal (UE) 3 in the cell (Cell # 2) of the unlicensed frequency (F2) in the second embodiment. Here, it is assumed that the radio base station (LTE-U eNB) 1 dynamically switches the operation of Cell # 2 based on the sensing results for other systems. For example, LTE-U eNB1 switches Cell # 2 On (in operation) and Off (in operation) by intermittently transmitting a predetermined reference signal (RS) in F2. The period during which the predetermined reference signal (RS) is transmitted in F2 corresponds to the On (operating) period of Cell # 2.

When the LTE-U eNB1 determines that Cell # 2 is turned on, the control signaling (L1 / L2 control signal) transmitted by the (U-) PDCCH using the above-mentioned U-RNTI is transmitted to the cell (eg Cell) of the license frequency. By transmitting in # 1), UE3 is instructed to measure the terminal in Cell # 2. When the UE 3 receives the control signaling, the UE 3 responds to the control signaling and makes a terminal measurement in the Cell # 2.

As a terminal measurement method in Cell # 2, for example, three methods shown in FIG. 5 can be considered. In the first method (option 1), after the UE 3 receives the (U-) PDCCH, the terminal measurement for the predetermined RS is performed only once in Cell # 2. In this method, the terminal measurement can be executed only once immediately after the UE3 receives the (U-) PDCCH (for example, after a few ms), and the terminal measurement report can also be executed in a short period of time. There is an advantage that Cell # 2 can be used immediately (if it meets the criteria for communication with # 2).

In the second method (option 2), after the UE 3 receives the (U-) PDCCH, the terminal measurement for the predetermined RS is performed a plurality of times in the Cell # 2. For example, UE3 refers to the primary terminal measurement (here, L1 measurement) of two measurements (ie two measurement samples) (or more), which is a requirement for terminal measurement used for cell (re) selection in LTE. ), And the process of averaging (L3 filtering) the results of those primary terminal measurements (secondary terminal measurement) may be executed. This method has an advantage that the reliability (accuracy) of the terminal measurement result is improved as compared with the first method. However, according to the requirements for terminal measurement used for cell (re) selection, etc., two measurements are set within about 200 ms, and the time constraint is relatively loose. Therefore, when reusing for LTE-U, the requirement for the period for performing the primary terminal measurement (L1 measurement) of two measurements (or more) is specified as, for example, within a dozen ms or a few tens of ms. Is preferable. The term "terminal measurement" refers to both the above-mentioned primary terminal measurement and secondary terminal measurement (that is, performing up to secondary terminal measurement), but is not limited to this.

In the third method (option 3), after UE3 receives the (U-) PDCCH, UE3 sends a predetermined signal (Synchronization signal, RS, and Master Information Block (MIB)) in Cell # 2. This is a method in which the terminal measurement is continued while the terminal measurement can be detected, and the terminal measurement is interrupted (stopped) when the terminal measurement cannot be detected. Here, it can be said that while UE3 is able to detect a predetermined signal is while UE3 is able to detect Cell # 2. For example, it is assumed that the reception quality (e.g. RSRP) of a predetermined RS (e.g. CRS) is equal to or higher than a predetermined threshold (e.g. -110 dBm). This method has an advantage that the reliability (accuracy) of the terminal measurement result is further increased as compared with the second method. On the other hand, a condition for continuing terminal measurement (or a condition for interrupting terminal measurement) so that UE3 does not continue terminal measurement after LTE-U eNB1 interrupts transmission of a predetermined RS in Cell # 2. Needs to be set correctly in UE3. Alternatively, the maximum number of terminal measurements or the maximum duration may be specified in advance in the specifications, or LTE-U eNB1 may notify UE3 of them.

Furthermore, if UE3 has received information (eg Duty Cycle Period and Duty Cycle) regarding the allocateable period of unlicensed frequencies to LTE-U in advance, UE3 will use the information to determine the duration of terminal measurement. You may judge. For example, if Duty Cycle Period = 100ms and Duty Cycle = 40% are specified, 40ms corresponds to the allottable period in 100ms cycle. When UE3 detects a predetermined signal (e.g. RS) in Cell # 2, the UE 3 may perform terminal measurement within 40 ms from that point (e.g. subframe number (subframe #)). Furthermore, UE3 may repeat the same operation in a cycle of 100 ms, that is, the terminal measurement may be interrupted for 60 ms after the terminal measurement during the first 40 ms, and the terminal measurement may be resumed during the next 40 ms. good.

The U-RNTI may be common to all wireless terminals 3 in the cell (serving cell; for example, Cell # 1 in Specific Example 2) in which the wireless terminal stays, or a plurality of limited radios in the cell. It may be common to the terminals 3 (terminal groups), or may be individual wireless terminals 3.

In addition, LTE-U eNB1 turns on the cell (eg Cell # 2) of the unlicensed frequency (eg F2) (that is, when it starts transmitting a predetermined signal (eg Synchronization signal, RS, and MIB)). (U-) PDCCH may be transmitted to, or (U-) PDCCH may be transmitted at an arbitrary timing while the cell is on.

<< Modification of Specific Example 2 >>
A modified example of the above-mentioned specific example 2 will be described. The difference from Specific Example 2 is that the (U-) PDCCH using U-RNTI, which indicates the instruction of terminal measurement in the cell (Cell # 2) of the non-licensed frequency (F2), relates to the measurement period in which the terminal measurement should be performed. It is a point that contains information. That is, when the radio base station (LTE-U eNB) 1 determines that Cell # 2 is turned on, the (U-) PDCCH using U-RNTI is used as the cell (eg Cell # 1) at the license frequency (eg F1). By transmitting in, the UE3 is instructed to measure the terminal in Cell # 2. Upon receiving the (U-) PDCCH, UE3 starts terminal measurement in Cell # 2, continues terminal measurement in Cell # 2 during the instructed measurement period, and obtains the result in the cell of the licensed frequency. Report to LTE-U eNB1 in (eg Cell # 1). By this method, LTE-U eNB can collect the result of the appropriate terminal measurement with the reliability (accuracy) of the expected terminal measurement.

Information on the measurement period is shown below, for example:
・ Combination of start timing and end timing of terminal measurement,
・ End timing of terminal measurement,
-Terminal measurement period, or-Information on the period when non-licensed frequencies can be assigned to LTE-U.

Information about the allottable period is, as described above, the Duty Cycle Period (in eg ms units), which corresponds to the reference period for defining the allocatable period, and the Duty Cycle, which corresponds to the percentage of the allocatable period in the reference period. It may contain either or both of (eg% units). That is, the Duty Cycle Period and Duty Cycle can be used to specify the period and duration of a periodic allocatable period.

The method of terminal measurement in Cell # 2 may differ depending on the information regarding the measurement period. For example, when the information regarding the measurement period indicates a combination of the start timing and the end timing of the terminal measurement, the wireless terminal 3 may start and end the terminal measurement according to the start and end timings. When the information about the measurement period indicates the end timing of the terminal measurement, the wireless terminal 3 starts the terminal measurement in response to the reception of the control signaling (L1 / L2 control signal) including the information about the measurement period, and is designated. The terminal measurement may be ended at the end timing. When the information about the measurement period indicates the period of the terminal measurement, the wireless terminal 3 may continue the terminal measurement from receiving the control signaling until the period expires.

Further, in the above-mentioned information regarding the measurement period, the information regarding the start timing, the end timing, the terminal measurement period, and the allocatable period may be defined using any or a combination of the following:
・ Unit time (ms),
-Subframe number (subframe #) or frame number (SFN),
・ Number of subframes or number of frames,
・ Subframe pattern or frame pattern,
・ Subframe offset or frame offset,
・ Absolute time,
-Relative time and-Percentage (%).

Here, the unit time may be, for example, us (microseconds) or s (seconds) other than ms (milliseconds). Subframe numbers (subframe #) are assigned from 0 (# 0) to 9 (# 9) in LTE, for example, and the length of each subframe is 1 ms. The frame number is, for example, the System Frame Number (SFN) in LTE, and the SFN is assigned from 0 (# 0) to 1023 (# 1023). Each frame is composed of 10 subframes (10 ms). The subframe offset or frame offset is effective when specifying a time point deviated by the value of the offset with respect to the subframe or the beginning of the frame (that is, # 0), for example, specifying the start timing of terminal measurement.

The subframe pattern or frame pattern indicates a subframe or frame for performing terminal measurement, and can be represented by, for example, a bitmap indicating each of 10 subframes or frames. For example, in the bit string, the bit corresponding to the subframe or frame on which the terminal measurement should be performed may be set to 1 (or 0), and the other bits may be set to 0 (or 1).

The absolute time is time information acquired by GNSS (Global Navigation Satellite System) such as GPS (Global Positioning System), and may be used to specify, for example, the start timing and / or end timing of terminal measurement. .. The relative time may represent the elapsed time from the time when the control signaling including the information about the measurement period is received (subframe) or the time when the control signaling can be detected (restored), and for example, the period for performing the terminal measurement is specified. May be used to

The percentage is used, for example, to indicate the duty cycle contained in the information about the allottable period of unlicensed frequencies to LTE-U. That is, the percentage can be used to specify the length of the periodic allottable period. The ratio to the allottable period may be defined by, for example, a decimal value (0.01, 0.02, ..., 010, .., 0.99, 1.00) other than the percentage (%). Also, if the maximum value of the Duty Cycle Period is MaxDutyCycle, the ratio can be expressed as an integer value (1, 2, ...., MaxDutyCycle) even if the value of the ratio (that is, equivalent to Duty Cycle) is expressed as an integer value (1, 2, ...., MaxDutyCycle). good. In this case, the percentage value effectively means the length of the ON period in the duty cycle, that is, the length of the non-licensed frequency allocatable period to LTE-U.

It should be noted that these are examples, and these illustrated parameters may be used in other uses. Further or in lieu of these, the information regarding the measurement period may include other parameters.

More specifically, when the information regarding the measurement period indicates the start timing and / or end timing of the terminal measurement, each of the start timing and the end timing may be expressed in a unit time (ms). For example, the radio base station 1 may specify "xx" and "yy" in the control information (field) for designating the start timing and the end timing, respectively, and the radio terminal 3 receives the control signaling including the information. The terminal measurement may be started after xx (ms) and ended after yy (ms) from the time when the signal is received (that is, the time when the signal is received or the time when the signal is detected). Instead, when each of the start timing and the end timing is represented by a subframe number, the radio base station 1 has, for example, "n" and "n" in the control information (field) that specifies the start timing and the end timing, respectively. You may specify "m", and the wireless terminal 3 may specify the latest time after the time when the control signaling including the information is received (that is, the received subframe or the subframe in which the reception is detected). Terminal measurement may be started from subframe #n and continued until subframe #m. The same applies when a frame number is used instead of the subframe number. Instead of these, when each of the start timing and the end timing is represented by an absolute time, the radio base station 1 may specify an absolute time indicating the start timing or the end timing, and the wireless terminal sets the absolute time. Terminal measurement may be started or stopped.

On the other hand, when the information regarding the measurement period indicates the period of terminal measurement, the period may be expressed in unit time (ms). For example, the wireless base station 1 may specify "zz" in the control information (field) that specifies the period, and the wireless terminal 3 receives the control signaling including the information (that is, the time of reception, that is, the time of reception. Alternatively, the terminal measurement may be performed between zz (ms) from the time when the reception is detected). Instead, when the terminal measurement period is represented by the number of subframes, the radio base station 1 may specify "N" in the control information (field) that specifies the period, and the radio terminal 3 may specify "N". The terminal measurement may be performed between the time when the control signaling including the information is received (that is, the received subframe or the subframe where the reception is detected) and the N subframe. Instead of these, when the terminal measurement period is represented by a subframe pattern, the radio base station 1 specifies a 10-bit bitmap (for example, "0000001111") in the control information (field) that specifies the period. The wireless terminal 3 may be set to "1" in the bitmap based on the time when the control signaling including the information is received (that is, the received subframe or the subframe in which the reception is detected). Terminal measurement is performed on the subfame # corresponding to the subframe. For example, when control signaling is received in subframe # 2, in the above example, the LSB (leftmost end) of the 10bit-bitmap corresponds to subframe # 2, and thereafter subframe # 3, 4, 5, 6, 7, 8, 9 Corresponds to, 0, 1. Alternatively, each bit of the bitmap may be fixedly assigned from the LSB to subframe # 0, 1, 2, ..., 9 in advance, and in the above example, subframe # 6, 7, 8, 9 is the measurement period. May be shown.

Further, a subframe offset may be used in conjunction with the subframe pattern to specify the period of terminal measurement. For example, the radio base station 1 may specify which subframe number (subframe #) the LSB (left end) of the above-mentioned 10-bit-bitmap corresponds to by the subframe offset. In the above 10bit-bitmap example, if start offset = 5 is specified, it means that the LSB corresponds to subframe # 5, and thereafter subframe # 6, 7, 8, 9, 0, 1, 2, 3 Corresponds to, 4. The subframe pattern may be represented by a bitmap of another number of bits (corresponding to 40 consecutive 40 subframes in a bitmap of eg 40 bits), or in another data format (for example, a subframe # corresponding to the terminal measurement period). It may be represented by enumeration). On the other hand, the same applies when a frame pattern is used instead of the subframe pattern, and a frame offset may be used at the same time. The frame pattern may also be represented by a bitmap or another data format.

Needless to say, the information regarding the measurement period in the above example and the specific data format for expressing the information are merely examples, and other combinations may be used.

<< Specific example 3 >>
Specific Example 3 in the first embodiment will be described. The difference from Specific Example 2 is the Media Access Control (MAC) layer transmitted on the Downlink Shared CHannel (DL-SCH) as control signaling for transmitting terminal measurement instructions at the unlicensed frequency (F2). The point is that the L2 control signal (MAC signaling) containing the control information (MAC Control Element: MAC CE) of is used. Then, in the control signaling, the Unlicensed Band Measurement MAC CE (or other names such as Unlicensed Frequency Measurement MAC CE, Unlicensed Spectrum Measurement MAC CE, LTE-U MAC CE, etc.) is an instruction for terminal measurement at an unlicensed frequency. It is used as the control information specified for this purpose. The value of the identifier (Logical Channel Identity: LCID) used to generate and restore the MAC Sub header corresponding to the Unlicensed Band Measurement MAC CE may be newly specified (for example, LCID Index = 11xxx (eg 11001)). for DL-SCH).

In Specific Example 3, when the wireless terminal (UE) 3 receives the control signaling (MAC signaling) and succeeds in restoring (detecting) the Unlicensed Band Measurement MAC CE, the cell (Cell # 2) of the unlicensed frequency (F2) ) Is instructed to perform terminal measurement. In order to realize this, the radio base station (LTE-U eNB) 1 previously provides the setting information (Measurement Configuration: MeasConfig) required for terminal measurement for the cell (Cell # 2) of the non-licensed frequency (F2) with the licensed frequency. In the cell (Cell # 1) of (F1), the wireless terminal (UE) 3 may be notified by, for example, RRC signaling.

In addition, the Unlicensed Band Measurement MAC CE contains information on the measurement duration of terminal measurements at unlicensed frequencies (e.g. F2). Here, the information regarding the measurement period may be the same as that described in the modified example of the specific example 2, or may be other than that.

FIG. 6 is a diagram for explaining terminal measurement by the wireless terminal (UE) 3 in the cell (Cell # 2) of the unlicensed frequency (F2) in the specific example 3. Similar to FIG. 5 relating to Specific Example 2, it is assumed that the radio base station (LTE-U eNB) 1 dynamically switches the operation of Cell # 2 based on the sensing results for other systems and the like. When the LTE-U eNB1 determines that Cell # 2 is turned on, it transmits control signaling (MAC signaling) including the above-mentioned Unlicensed Band Measurement MAC CE in the cell (eg Cell # 1) of the license frequency to perform UE3. Is instructed to measure the terminal in Cell # 2. When the UE 3 receives the control signaling, the UE 3 responds to the control signaling and makes a terminal measurement in the Cell # 2. Here, the control signaling includes information about the measurement period, and the UE 3 performs terminal measurement accordingly.

Similar to the description in the modified example of the specific example 2, the method of terminal measurement in Cell # 2 may be different depending on the information regarding the measurement period. However, in the specific example 3, since the control signaling (MAC signaling) is different from the modified example of the specific example 2, there is a point that different operations are performed due to this difference. For example, if the start timing of the terminal measurement is not explicitly specified, the terminal measurement responds to the fact that the control information (Unlicensed Band Measurement MAC CE) transmitted by the control signaling can be correctly detected (decoded) in UE3. It may be started. Alternatively, the start point of the measurement period (measurable period) of the terminal measurement may be the time when the control information (Unlicensed Band Measurement MAC CE) transmitted by the control signaling can be correctly detected (decoded) in UE3.

<< Specific example 4 >>
A specific example 4 in the first embodiment will be described. The difference from Specific Examples 1 to 3 is that the wireless terminal (UE) 3 performs terminal measurement at an unlicensed frequency (F2) (cell (Cell # 2)) as specified in advance. Specifically, the wireless base station (LTE-U eNB) 1 sets the wireless terminal (UE) 3 in advance with the setting information (Measurement Configuration:) required for terminal measurement in the cell (Cell # 2) of the unlicensed frequency (F2). MeasConfig) is sent by RRC signaling etc. Further, LTE-U eNB1 includes the setting information (Measurement Gap Configuration: MeasGapConfig) of the terminal measurement gap used for the terminal measurement in the MeasConfig.

In the specific example 4, similarly to the specific example 2, L1 transmitted on the downlink physical control channel (PDCCH or the above-mentioned U-PDCCH) as the control signaling for transmitting the terminal measurement instruction at the unlicensed frequency (F2). / L2 control signal is used. Then, the control signaling (L1 / L2 control signal) is transmitted using the above-mentioned U-RNTI. Further, in the fourth embodiment, the control signaling includes an execution instruction of the terminal measurement gap (that is, an instruction of activation of the terminal measurement gap). The terminal measurement gap execution instruction corresponds to information about the measurement period. The execution instruction of the terminal measurement gap may, for example, instruct to execute the terminal measurement according to the previously notified (designated) MeasGapConfig. Further, when LTE-U eNB1 notifies UE3 of a plurality of MeasGapConfig (that is, a pattern of the terminal measurement gap) in advance, the execution instruction of the terminal measurement gap may indicate which MeasGapConfig is used to execute the terminal measurement. ..

FIG. 7 is a diagram for explaining terminal measurement by the wireless terminal (UE) 3 in the cell (Cell # 2) of the unlicensed frequency (F2) in the specific example 4. Similar to FIGS. 5 and 6 relating to Specific Examples 2 and 3, it is assumed that the radio base station (LTE-U eNB) 1 dynamically switches the operation of Cell # 2 based on the sensing results for other systems. .. The LTE-U eNB1 first transmits MeasConfig including MeasGapConfig to UE3 in the cell (e.g. Cell # 1) of the license frequency. When the LTE-U eNB1 determines that Cell # 2 is turned on, the control signaling (L1 / L2 control signal) transmitted by the (U-) PDCCH using the above-mentioned U-RNTI is transmitted to the cell (eg Cell) of the license frequency. By transmitting in # 1), UE3 is instructed to measure the terminal in Cell # 2. When UE3 receives the control signaling, it responds and performs terminal measurement in Cell # 2 according to Measurement Gap specified by MeasureGapConfig.

FIG. 7 shows a case where the terminal measurement gap length (Measurement Gap Length) is 6 ms as an example. Upon receiving the control signaling ((U-) PDCCH) and recognizing that the UE3 has received the terminal measurement instruction of Cell # 2, the UE3 immediately activates the terminal measurement gap and starts the terminal measurement. Then, UE3 executes the terminal measurement of Cell # 2 for 6 ms according to the Measurement Gap Length. The target of the terminal measurement may be a plurality of cells at one unlicensed frequency (F2), or may be a plurality of cells at a plurality of unlicensed frequencies.

As a result, the terminal measurement can be dynamically executed while maintaining the reliability (accuracy) required for the terminal measurement in the cell (Cell # 2) of the non-licensed frequency (F2).

In FIG. 7, each time the wireless terminal 3 receives the control signaling, one-time terminal measurement (that is, over the length of the terminal measurement gap in one terminal measurement gap) using the terminal measurement gap (one-shot). An example of executing UE measurement with measurement gap) is shown. However, the wireless terminal 3 may execute terminal measurement (multiple UE measurements with periodic measurement gap) using the terminal measurement gap a plurality of times in a predetermined cycle each time the control signaling is received. For example, the wireless base station 1 may notify the wireless terminal 3 in advance how many times the terminal measurement using the terminal measurement gap is performed, or how long the terminal measurement is performed.

Further, the wireless base station 1 notifies the wireless terminal 3 in advance of the setting information (MeasGapConfig) of the terminal measurement gap of a plurality of patterns and the index for identifying each of the plurality of patterns, and determines which pattern of the terminal measurement gap. Whether to execute may be specified in the control signaling ((U-) PDCCH) with the corresponding index.

Further, the wireless base station 1 uses the terminal measurement gap setting information (MeasGapConfig) to wait for the wireless terminal 3 to execute the terminal measurement gap after receiving the control signaling ((U-) PDCCH). The wireless terminal 3 may be notified of the activation time) or the start offset (GapOffset) in executing the terminal measurement gap.

Further, the radio base station 1 may specify information regarding the measurement period similar to the modification of the specific example 2 by the control signaling. For example, when the start timing and / or end timing of the terminal measurement are specified, the start and end timings of the terminal measurement may indicate the start and end timings of the terminal measurement gap, respectively. When a terminal measurement period is specified, the period may indicate a period during which the terminal measurement gap is valid (that is, terminal measurement is performed using the terminal measurement gap).

<< Modification of Specific Example 4 >>
A modified example of the above-mentioned specific example 4 will be described. The difference from the specific example 4 is that the control signaling indicating the terminal measurement instruction in the cell (Cell # 2) of the non-licensed frequency (F2) is the L2 control signal (MAC signaling). For example, it can be realized by adding the information transmitted by the (U-) PDCCH described in the specific example 4 to the Unlicensed Band Measurement MAC CE illustrated in the specific example 3. Since other details are the same as those of Specific Example 4, the description thereof will be omitted.

The terminal measurement described above may be, for example, the calculation of the instantaneous measurement value of the reception quality of the reference signal, the primary measurement (L1 filtering), or the secondary measurement (L3 filtering). But it may be. Further, the content of the terminal measurement in the following description may be different from the specific example of the content of the terminal measurement described above.

<Second embodiment>
A second embodiment of the present invention will be described. In the present embodiment, the radio base station selects the radio terminal (UE) 3 to be instructed to measure the terminal before the terminal measurement in the cell of the non-licensed frequency described in the first embodiment is performed. (LTE-U eNB) 1 performs. Specifically, it will be described with reference to FIG. In FIG. 8, it is assumed that LTE-U eNB1 manages a cell (Cell # 1) at a licensed frequency (F1) and a cell (Cell # 2) at a non-licensed frequency (F2). In the present embodiment, the wireless terminal (UE) 3 has a detection function for detecting proximity to a cell of an unlicensed frequency and a reporting function for reporting the result to a wireless base station if it can be detected. The cell of the non-licensed frequency will be described below assuming that it is a non-serving cell for the wireless terminal, but it is a serving cell or a configured cell. You may. The wireless terminal 3 is displayed as UE # 1 in FIG.

In FIG. 8, first, UE3 establishes a wireless connection with LTE-U eNB1 (RRC Connection Establishment) in Cell # 1 of the serving cell, and bearer (eg EPS bearer,) between the core network (EPC). E-RAB) is established (not shown). After that, for example, user data can be transmitted and received. The LTE-U eNB1 performs first channel sensing at unlicensed frequencies (e.g. F2) (Perform first channel sensing, S301). Here, the first sensing includes CAC for a radar system, CCA for another system such as WLAN, CCA for LTE-U by another operator (service provider), or two or all of them.

When the LTE-U eNB1 determines that the unlicensed frequency (eg F2) can be used by the first sensing (S301), the LTE-U eNB1 determines that the non-licensed frequency (eg F2) can be used. ) Is notified (Proximity configuration for unlicensed frequency, S302). Upon receiving the notification (ie, in response to the notification), UE3 attempts to detect proximity to the cell (eg Cell # 2) at the unlicensed frequency (eg F2) (ie, enables the detection feature (ie). Activate)). When UE3 can detect a non-attributive cell at a non-licensed frequency (Proximity detection on unlicensed frequency (cell), S303), it reports the result of the detection to LTE-U eNB (Proximity indication for unlicensed frequency, S304).

Here, the notification regarding the detection of proximity to a cell of a non-licensed frequency may include, for example, at least one of the information of one or more non-licensed frequencies of interest and the information of the cell at the non-licensed frequency. Information on unlicensed frequencies may be presented, for example, in any or combination of the following:
・ LTE frequency identifier (eg EARFCN),
-Unlicensed frequency index, and- (center) frequency (eg carrier frequency).
The unlicensed frequency identifier may be defined by adding a new number or index to the unlicensed frequency that can be used in LTE-U.

Cell information at unlicensed frequencies may be presented, for example, in any or combination of the following:
• Cell identifier (eg PCI, ECGI, or Virtual Cell ID), and • Unlicensed frequency cell identifier (eg Unlicensed Cell ID).
The Virtual Cell ID may be, for example, a scrambling code identifier (eg Scrambling Identity or Scrambling Code ID) used for transmitting a reference signal in the cell of the non-licensed frequency. Further, the non-licensed frequency cell identifier may be defined by newly assigning a cell number or a cell index to the cell of the non-licensed frequency.

Furthermore, the notification may include other network identifiers (e.g. PLMN ID, TAI, or TAC). When the notification includes these network identifiers, the wireless terminal 3 may determine that the cell is the target of detection of proximity to the cell based on the fact that the designated network identifier can be confirmed in the cell.

The explanation will be continued by returning to FIG. Based on the report, LTE-eNB1 decides to instruct UE3 to perform terminal measurement in the cell (eg Cell2) of the unlicensed frequency (eg F2) (Decision on UE measurement in unlicensed frequency for UE # 1, S305). ). Then, LTE-eNB1 and UE3 execute the procedure for terminal measurement reporting for unlicensed frequencies as in the first embodiment (Measurement Configuration, Instruction and Reporting for Unlicensed Frequency, S306).

As shown in FIG. 8, in this embodiment, the radio base station (LTE-U eNB) 1 is in close proximity to a non-attributable cell at an unlicensed frequency (eg F2) prior to transmitting control signaling. Is received from the wireless terminal (UE) 3, and the transmission of the control signaling to the wireless terminal (UE) 3 is determined based on the detection result of the proximity (or in response to the detection result of the proximity). Therefore, for example, the radio base station (LTE-U eNB) 1 can be expected to have a throughput improvement effect by LTE-U based on the detection result of proximity to the cell (eg Cell2) of the unlicensed frequency (eg F2). Can be determined. Therefore, the radio base station (LTE-U eNB) 1 provides, for example, a terminal measurement report for determining whether or not LTE-U using a cell at an unlicensed frequency is permitted to the radio terminal (UE) 3. Only UE3, which can be expected to improve the throughput by LTE-U, can be selectively performed. As a result, it can be expected that the power consumption and the control information associated with the terminal measurement report will be reduced for UE3, which does not require the terminal measurement report. This is particularly effective when the operation of the cell at the non-licensed frequency is dynamically switched, that is, when the cell On / Off is switched irregularly.

Here, the detection of proximity (proximity) to a cell at an unlicensed frequency by the above-mentioned wireless terminal (UE) detects, for example, a cell identification signal transmitted from a wireless base station (LTE-U eNB) 1 in the cell. Including doing. The cell-specific signal includes at least one of a known symbol and a known sequence. The cell specific signal may be, for example, a synchronization signal (Synchronization Signal. In LTE, there are Primary SS: PSS and Secondary SS: SSS) or a reference signal (Reference Signal: RS), or basic information (notified in the cell). It may be Master Information Block (MIB) or System Information Block (SIB, for example SIB1 or SIB2, or SIBx specified for LTE-U). In this case, the wireless terminal 3 has, for example, whether or not the reception quality (eg RSRP, RSRQ, RSSI, SINR, or CQI) of the cell specific signal (eg RS) is equal to or higher than a predetermined threshold value (or whether or not it is larger than the threshold value). The proximity of the unlicensed frequency to the cell may be detected based on. Instead, the wireless terminal 3 may detect proximity to the cell based on whether or not it has correctly received the basic information (MIB) or system information (SIB) broadcast in the cell. The reference signals include, for example, a cell specific reference signal (Cell Specific RS: CRS), a reference signal for measurement reporting of channel state information (CSI) (CSI RS), and a reference signal for cell detection (CSI RS). Discovery RS: DRS) may be included at least. The DRS may be a combination of two or more of, for example, PSS, SSS, CRS, and CSI RS, or may be a newly defined reference signal for cell detection.

When the wireless terminal (UE) 3 receives a notification regarding detection of proximity to a cell at a non-licensed frequency transmitted from the radio base station (LTE-U eNB) 1, it should perform detection at the non-licensed frequency. It may be considered that it was set to (UE considers itself to be configured to perform proximity check for unlicensed frequency), and it is set to give a notification (proximity indication) indicating that the proximity to the cell at the non-licensed frequency has been detected. It may be considered that it was done (UE considers itself to be configured to provide proximity indication for unlicensed frequency). The "proximity check" is also called "proximity estimation". Further, the radio base station (LTE-U eNB) 1 may explicitly instruct the detection to be performed in the notification, or information on the non-licensed frequency to be detected or the non-licensed frequency. The notification may be implicitly instructed to perform the detection by including information about the cell in the notification.

Further, the notification regarding the detection of proximity to the cell at the unlicensed frequency may be transmitted as individual control information by, for example, RRC signaling (message). In this case, the RRC message corresponding to the notification may be an RRC Connection Reconfiguration message, and ReportProximityUnlicensedConfig IE may be newly defined as the RRC information element (IE) included therein. The IE includes information on the target unlicensed frequency, as well as information that enables the ability to detect proximity to cells of unlicensed frequencies (proximityIndicationUnlicensed set to enabled). In addition, the RRC message may transmit cell identification information at unlicensed frequencies, such as a Physical Cell Identifier (PCI) or EUTRAN Cell Global ID (ECGI). The notification may be transmitted by notification information (System Information: SI, System Information Block: SIB) instead of RRC signaling.

On the other hand, a notification (proximity indication) indicating that the proximity to the cell at the unlicensed frequency has been detected may also be transmitted by RRC signaling (message). In this case, a ProximityIndicationUnlicensed message may be newly specified as the RRC message corresponding to the notification. The message includes Proximity Indication Unlicensed IE as an IE indicating the result of detection of proximity to a cell of unlicensed frequency. The IE may include information indicating that it has been detected and information on the target unlicensed frequency. The IE may include cell identification information (e.g. PCI or ECGI) at the detected unlicensed frequency.

Note that the detection of proximity to a cell corresponds to detecting that the wireless terminal 3 has entered the proximity (area / range) of one or more cells at a target unlicensed frequency, but is wireless. The case where the terminal 3 is already in the proximity of the cell before starting (attempting) the detection of the proximity to the cell is also included in the scope of application of the present embodiment. The detection of proximity to a cell can also be referred to (thinking) as estimation of proximity to a cell (Estimation), detection of cell availability (Availability), or simply detection of a cell (Discovery). ..

<Third embodiment>
A third embodiment of the present invention will be described. FIG. 9 is a diagram showing a configuration example of an LTE-U wireless communication system and other systems targeted by a plurality of embodiments including the present embodiment. The main difference from FIGS. 1A and 1B is that the radio base stations (eNB) 6 and 7 and the radio terminal (UE) 8 have a dual connectivity (DC) function (Non-Patent Document 5). Dual Connectivity is each radio resource (ie, managed) provided (ie, managed) by the main base station (master base station, Master eNB: MeNB) 6 and the sub base station (secondary base station, Secondary eNB: SeNB) 7. , Cell or carrier) at the same time, and the UE8 communicates with each other. In the example of FIG. 9, MeNB 6 and SeNB 7 are connected via the X2 interface, MeNB 6 manages Cell # 1 with license frequency F1, and SeNB 7 manages Cell # 2 with license frequency F2 and Cell # 3 with unlicensed frequency F3. to manage. Note that MeNB 6 and SeNB 7 operate as normal LTE eNB for UEs that do not perform DC, and can communicate with UEs independently in Cell # 1 and Cell # 2, respectively.

Next, Dual Connectivity will be briefly described. The UE 8 can perform carrier aggregation (CA) in which a plurality of cells managed by MeNB 6 and SeNB 7 having different frequencies are simultaneously used as serving cells. The set of serving cells managed by MeNB6 is called the Master Cell Group (MCG), and the set of serving cells managed by SeNB7 is called the Secondary Cell Group (SCG). The MCG includes at least a Primary Cell (PCell) and may further include one or more Secondary Cells (SCells). The SCG includes at least a Primary SCell (abbreviated as pSCell or PSCell), and may further include one or more SCells. A pSCell is a cell to which at least a physical uplink control CHannel (PUCCH) is assigned and has a role similar to PCell in SCG.

The MeNB 6 maintains a connection (S1-MME) with the mobility management Entity (MME) of the core network (Evolved Packet Core: EPC) for the UE 8 that executes the DC. Therefore, MeNB6 can be called a mobility management point (or mobility anchor) of UE8. Therefore, the control plane (CP) control information is transmitted and received between MeNB 6 and UE 8 in the MCG. CP control information related to SCG of SeNB7 is transmitted and received between SeNB7 and MeNB6 (X2 interface), and further transmitted and received between MeNB6 and UE8 in MCG. For example, SCG's Radio Resource Configuration (eg RadioResoureConfigDedicated IE) is transmitted from SeNB 7 to MeNB 6 by an inter-node RRC message called SCG-Configuration, and is transmitted from MeNB 6 to UE 8 by an RRC Connection Reconfiguration message. On the other hand, UE8 terminal capability information (UE-EUTRA capabilities IE), SCG security information (eg SK _eNB ), MCG Radio Resource Configuration (eg RadioResourceConfigDedicated IE), etc. are MeNB6 in an inter-node RRC message called SCG-ConfigInfo. Is transmitted to SeNB7.

The DC supports three configurations in terms of User Plane (UP) bearer settings. The first is the MCG bearer. The MCG bearer is a bearer whose wireless protocol is located only in MeNB6 because it uses only the resources (eg MCG) of MeNB6, and is a gateway device (S-GW or S-GW or A connection (S1-U) is maintained between P-GW) and MeNB6. The second is the SCG bearer. The SCG bearer is a bearer whose wireless protocol is located only in SeNB7 in order to use only the resources (eg SCG) of SeNB7, and is connected between the gateway device (S-GW or P-GW) and SeNB7 (SCG bearer). S1-U) is retained. The third is the Split bearer. A split bearer is a bearer whose radio protocol is located on both MeNB6 and SeNB7 in order to use both MeNB6 and SeNB7 resources (e.g. MCG and SCG). In Split bearer, the connection (S1-U) is maintained between the gateway device (S-GW or P-GW) and MeNB6. For example, UP data (eg PDCP PDU) transmitted by SCG is sent via X2 to MeNB6. Is transferred to SeNB 7.

Next, the details of this embodiment will be described. In the example of DC in FIG. 9, when Cell # 3 of the unlicensed frequency F3 of SeNB7 is carrier-aggregated with Cell # 2 of the licensed frequency F2 of SeNB7 to realize LAA, the first and second implementations described above are performed. There is a possibility that the problem cannot be solved only by the technology shown in the form. This is because the SeNB 7 cannot directly send and receive CP control information (e.g. RRC, NAS) to and from the wireless terminal (UE8) when DC is performed. The setting information (MeasConfig) for terminal measurement and the report of terminal measurement result (Measurement report) correspond to the control information of CP. Therefore, a control procedure for solving a further problem in DC will be described with reference to FIG. FIG. 10 is a sequence diagram showing the operations of the radio base stations (MeNB6, SeNB7) and the radio terminal (UE) 8 in the third embodiment. The wireless terminal (UE) 8 is displayed as UE # 2 in FIG.

First, UE8 establishes a wireless connection (RRC Connection) using Cell # 1 of MeNB6 as a PCell, and makes the necessary settings for Dual Connectivity (DC) so that Cell # 2 of SeNB7 can be used as a pSCell (Dual Connectivity Configuration, S401). Then, MeNB6 or SeNB7 determines whether or not UE8 is allowed to perform terminal measurement at an unlicensed frequency (e.g. F3) (Decision on UE measurement in unlicensed frequency for UE # 2, S402). When it is decided to perform the terminal measurement, the MeNB 6 uses the RRC Connection Reconfiguration message in Cell # 1, for example, the setting information (Measurement configuration: MeasConfig) required for the terminal measurement at the unlicensed frequency (eg F3). To UE8 (Measurement Configuration for Unlicensed Frequency (eg Cell # 3 on F3), S403). The Measurement configuration may be generated by SeNB 7 and notified to MeNB 6, or may be generated by MeNB 6. When the MeNB 6 reports the completion of the reception of the setting information (and the setting change (reconfiguration) according to the setting information) from the UE 8, the MeNB 6 may notify the SeNB 7 of the completion (Measurement Configuration Complete, S404). Here, the notification of S404 may be included in the SCG-ConfigInfo of the inter-node RRC container and sent. In addition, this may be sent via the SeNB RECONFIGURATION COMPLETE message on the X2 interface (X2AP).

Then, SeNB7 gives an instruction for terminal measurement in a cell (eg Cell # 3 on F3) of a non-licensed frequency by a predetermined control signaling in Cell # 2 (Measurement Instruction for Unlicensed Frequency (eg Cell # 3 on F3). S405). Here, the terminal measurement instruction indicates the timing at which the UE8 should measure the terminal measurement at the Unlicensed Frequency (for example, Cell # 3 of F3) (that is, the terminal measurement should be executed), and the measurement timing. It is associated with at least one of the measurement periods, which indicates which period should be measured (ie, it is reasonable to perform terminal measurements). In other words, the terminal measurement instruction (S405) explicitly or implicitly indicates at least one of the measurement timing and measurement period (measurable period) of the terminal measurement at the Unlicensed Frequency (for example, Cell # 3 of F3) by UE8. Shown. Since the details of the measurement timing and the measurement period are the same as those described in the first embodiment, the description thereof will be omitted. Here, the control signaling of S405 may be transmitted by MeNB6. In this case, SeNB 7 may transmit at least a part of the information to be transmitted in the control signaling to MeNB 6, MeNB 6 may transmit the information to UE 8, and MeNB 6 itself may transmit the information to be transmitted in the control signaling. It may be generated.

UE8 performs terminal measurement in Cell # 3 in response to the control signaling (S405), that is, according to the instruction of the terminal measurement (Measurement, S407), and reports the result of the terminal measurement to MeNB in Cell # 1. (Measurement Reporting for Unlicensed Frequency (eg Cell # 3 on F3), S408). The UE 8 may measure the reception strength or the reception quality of the reference signal (S406) transmitted from the SeNB 7 in the Cell # 3 in the terminal measurement (S407), for example. The terminal measurement and the terminal measurement report may be performed not only on the cell (Cell # 3) of the non-licensed frequency (F3) but also on another cell of F3, another unlicensed frequency, or a licensed frequency. Further, since the details of the terminal measurement are the same as those described in the first embodiment, the description thereof will be omitted.

On the other hand, MeNB6 or SeNB7 determines whether or not to perform communication with UE8 in Cell # 3 (for example, downlink data transmission) based on the reported terminal measurement result. When MeNB6 or SeNB7 determines that communication with UE8 is performed in Cell # 3 managed by SeNB7 (Decision on LTE-U for UE # 2 in Cell # 3, S409), MeNB6 is Cell # 1 in Cell # 1. The radio resource configuration information (Radio Resource Configuration, eg RadioResourceConfigCommon, RadioResourceConfigDedicated) of 3 is transmitted to UE8 (Radio Resource Configuration for Cell # 3, S410). At this time, MeNB 6 may use, for example, an RRC Connection Reconfiguration message. The radio resource setting information of the Cell # 3 may be generated by SeNB 7 and transferred to MeNB 6 as SCG-Configuration, and the MeNB 6 may transmit the radio resource setting information to UE 8. Then, SeNB 7 transmits, for example, user data (DL data) to UE 8 by LAA that Carrier Aggregates Cell # 2 and Cell # 3 (not shown).

By the above procedure, it is possible to appropriately determine the wireless terminal 3 for which LTE-U is permitted at (cell) of the unlicensed frequency managed by SeNB 7 even while Dual Connectivity is being executed. As a result, improvement of the overall characteristics of the LTE wireless communication system, for example, system throughput can be expected.

<< Specific example 5 >>
A specific example 5 in the third embodiment will be described. In Specific Example 5, a procedure for determining whether or not to allow UE 8 to perform terminal measurement at a non-licensed frequency (eg F3) will be described in MeNB 6 or SeNB 7.

FIG. 11 is a diagram showing an example of the operation of MeNB 6 and SeNB 7 including the exchange of information (X2 message) in Step S402 “Decision on UE measurement in unlicensed frequency for UE # 2” of FIG. There are two options for the operation of MeNB6 and SeNB7. In the first option (Option 1), SeNB 7 decides whether to let the UE 8 perform terminal measurements at unlicensed frequencies (e.g. F3) (Decision on UE measurement, S501). When SeNB7 decides to perform the terminal measurement, it notifies MeNB6 of the information of the target unlicensed frequency (Available Unlicensed Frequency Information, S502). MeNB6 may respond to the notification (S502) (Available Unlicensed Frequency Information Response, S503).

On the other hand, in the second option (Option 2), SeNB 7 notifies MeNB 6 of information on the target unlicensed frequency (Available Unlicensed Frequency Information, S505), and MeNB 6 makes the decision (S506). Then, MeNB 6 transmits the result of the determination to SeNB 7 (Available Unlicensed Frequency Information Response, S507). Here, the result of the determination may include information indicating that the UE 8 is to perform terminal measurement at an unlicensed frequency, or may simply include an acknowledgment (ACK). The above-mentioned information on the target non-licensed frequency may be the information on the non-licensed frequency (eg EARFCN, Unlicensed frequency index, or carrier frequency) or the information on the cell at the non-licensed frequency (eg PCI, ECGI, Virtual Cell). ID, or Unlicensed Cell ID), or a combination thereof. In addition, information on unlicensed frequencies in S502 and S505 may be transmitted in the ENB CONFIGURATION UPDATE message of the X2AP. In particular, the information may be included in the Served Cells To Add IE or Served Cells To Modify IE of the message.

<< Specific example 6 >>
A specific example 6 in the third embodiment will be described. Specific Example 6 describes a procedure for determining whether or not LTE-U in a cell with an unlicensed frequency (eg Cell # 3 on F3) is permitted to UE8 in MeNB6 or SeNB7.

FIG. 12 is a diagram showing an example of the operation of MeNB 6 and SeNB 7 including the exchange of information (X2 message) in Step S409 “Decision on LTE-U for UE # 2 in Cell # 3” of FIG. There are two options for the operation of MeNB6 and SeNB7. In the first option (Option 1), the MeNB 6 first transmits the terminal measurement results at the unlicensed frequency received from the UE 8 to the SeNB 7 (Measurement results for unlicensed frequency, S601). SeNB7 determines whether or not to allow UE8 LTE-U in a cell (Cell # 3 on F3) of an unlicensed frequency to UE8 based on the result of the terminal measurement (Decision on LTE-U, S602). .. When SeNB7 decides to allow UE8 to perform LTE-U, it generates radio resource setting information (eg RadioResourceConfigCommon, RadioResourceConfigDedicated) of the target unlicensed frequency cell (Cell # 3) and sends it to MeNB6. (Radio resource configuration for Cell # 3, S603).

Here, the result of the terminal measurement of S601 may be included in the SCG-ConfigInfo of the inter-node RRC container and transmitted. In addition, this may be sent in the X2AP SeNB MODIFICATION REQUEST message. Further, the radio resource setting information of S603 may be included in the SCG-Configuration of the inter-node RRC container and transmitted. In addition, it may be sent in the X2AP SeNB MODIFICATION REQUEST ACKNOWLEDGE message or in the SeNB MODIFICATION REQUIRED message.

On the other hand, in the second option (Option 2), MeNB6 decides whether to allow LTE-U in the unlicensed frequency cell (Cell # 3 on F3) to UE # 2 based on the result of terminal measurement. (Decision on LTE-U, S605). When MeNB6 decides to allow LTE-U to UE8, it sends a request to SeNB7 to add the target non-licensed frequency cell (Cell # 3) to the belonging cell (serving cell. Eg SCG) (Cell). # 3 addition request, S606). The information of Cell # 3 in the request may be indicated by the information of the non-licensed frequency (e.g. EARFCN) and PCI of Cell # 3, ECGI of Cell # 3, or a combination thereof. In response to the request, SeNB7 generates radio resource setting information (e.g. RadioResourceConfigCommon, RadioResourceConfigDedicated) of Cell # 3 and transmits it to MeNB6 (Radio resource configuration for Cell # 3, S607).

Here, the S606 request may be included in the SCG-ConfigInfo of the inter-node RRC container and sent. In addition, this may be sent in the X2AP SeNB ADDITION REQUEST message or SeNB MODIFICATION REQUEST message. Further, S607 may be included in SCG-Configuration and transmitted in the same manner as S603. In addition, this may be sent in the X2AP SeNB ADDITION REQUEST ACKNOWLEDGE message or SeNB MODIFICATION REQUEST ACKNOWLEDGE message.

Finally, a configuration example of the wireless base stations (LTE-U eNB1, MeNB6, SeNB7) and the wireless terminals (UE3, UE8) according to the above-described embodiment will be described. Each of the radio base stations (LTE-U eNB1, MeNB6, SeNB7) described in the above-described embodiment may include a transceiver for communicating with a radio terminal (UE3, UE8) and a controller coupled to the transceiver. good. The controller is a control for performing terminal measurement at a non-licensed frequency in a wireless terminal (UE3, UE8) regarding a control procedure (for example, terminal measurement at an unlicensed frequency) relating to a radio base station (LTE-U eNB1, MeNB6, SeNB7) described in the above embodiment. ) Is executed.

Each of the radio terminals (UE3, UE8) described in the above-described embodiment may include a transceiver for communicating with a radio base station (LTE-U eNB1, MeNB6, SeNB7), and a controller coupled to the transceiver. good. The controller executes the control procedure (eg, control of terminal measurement and report of terminal measurement) relating to the wireless terminals (UE3, UE8) described in the above-described embodiment.

13 and 14 are block diagrams showing a configuration example of the radio base station 1 and the radio terminal 3 according to the first embodiment. The radio base station and the radio terminal according to other embodiments may have the same configurations as those in FIGS. 13 and 14. Referring to FIG. 13, radio base station 1 includes transceiver 101 and controller 102. The transceiver 101 is configured to communicate with a plurality of wireless terminals including the wireless terminal 3. The controller 102 is configured to transmit a notification to the wireless terminal 3 and receive a measurement report from the wireless terminal 3 in order to perform terminal measurement by the wireless terminal 3 at a non-licensed frequency.

Referring to FIG. 14, the wireless terminal 3 includes a transceiver 301 and a controller 302. The transceiver 301 is configured to communicate with the radio base station 1. The controller 302 is configured to control the terminal measurement at the non-licensed frequency according to the notification received from the radio base station 1 and transmit the measurement report to the radio base station 1.

Each of the controllers implemented in the radio base station and the radio terminal according to the above-described embodiment is programmed into a computer including at least one processor (eg processor, Micro Processing Unit (MPU), Central Processing Unit (CPU)). It may be realized by executing it. Specifically, one or a plurality of programs including a group of instructions for causing the computer to perform the algorithms related to UE and eNB described by using the sequence diagram or the like may be supplied to the computer.

This program can be stored and supplied to a computer using various types of non-transitory computer readable medium. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical disks), Compact Disc Read Only Memory (CD-ROM), CD- Includes R, CD-R / W, semiconductor memory (eg, mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access Memory (RAM)). The program may also be supplied to the computer by various types of transient computer readable medium. Examples of temporary computer-readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

<Other Embodiments>
In the first to third embodiments, it has been described assuming that an unlicensed frequency is used for transmitting downlink user data. However, it goes without saying that these embodiments can be applied even when an unlicensed frequency is used for uplink user data transmission. At this time, the wireless terminal (UE) 3 may perform the same processing as the first sensing or the second sensing performed by the wireless base station (LTE-U eNB) 1. As a result, it is possible to prevent the characteristics of not only the LTE-U system but also other systems from being deteriorated due to excessive interference of the LTE-U uplink signal transmission with other systems.

Further, in the first to third embodiments, the case of LAA has been described. That is, in the first and second embodiments, the radio base station (LTE-U eNB) 1 and the radio terminal (UE) 3 use the licensed frequency cell as the primary cell (PCell), and the non-licensed frequency cell. Was mainly described for carrier aggregation (CA) using as a secondary cell (SCell). In the third embodiment, Dual Connectivity (DC) in which MeNB 6 and SeNB 7 use the licensed frequency and SeNB 7 further uses the non-licensed frequency has been mainly described. However, as already mentioned, in the first and second embodiments, the radio base station (LTE-U eNB) 1 uses a shared frequency (eg F3) as the PCell and is a narrowly defined unlicensed frequency (eg F3). Carrier aggregation (CA) may be performed using F2) or another shared frequency (eg, F4) as the secondary cell (SCell). Here, the non-licensed frequency in a narrow sense means a frequency that is not assigned to any operator (that is, a frequency that is neither a licensed frequency nor a shared frequency). In this case, the radio base station (LTE-U eNB) 1 sends control signaling associated with at least one of the measurement timing or measurement period of the terminal measurement in the SCell (eg F2 or F4) to the radio terminal 3 in the PCell (eg F3). May be sent to. Similarly, in a third embodiment, for Dual Connectivity (DC), MeNB 6 may use a shared frequency and SeNB 7 may use a shared frequency or a narrowly defined unlicensed frequency.

Further, in the above-described embodiment, the LTE system has been mainly described. However, as already mentioned, these embodiments may be applied to wireless communication systems other than LTE systems, such as 3GPP UMTS, 3GPP2 CDMA2000 systems (1xRTT, HRPD), GSM / GPRS systems, WiMAX systems, etc. good. The radio base station (eNB) and RRH / RRE having the function of performing LTE communication at unlicensed frequencies are called radio base stations (LTE-U eNB). Similarly, in other systems, it is possible to introduce network devices capable of communicating at non-licensed frequencies using the same communication method (function) as the licensed frequency, and these are collectively called radio stations. Can be done. That is, the radio station corresponds to a radio base station (eNB) and RRH / RRE in LTE as described above, corresponds to a base station (NodeB: NB) and a base station control station (RNC) in UMTS, and further corresponds to CDMA2000. In the system, it corresponds to a base station (BTS) and a base station control station (BSC). Furthermore, especially in the example of Dual Connectivity (DC), a base station system including a main base station (MeNB in LTE) and a sub base station (SeNB in LTE) can be called a radio station. Each of the main base station and the sub base station can be referred to as a wireless communication node.

Also, in the above-described embodiment, the cell of the license frequency to which the control signaling for the terminal measurement instruction is transmitted (that is, the cell operated by PCell at CA or MeNB at the time of DC) and the terminal measurement The cells of the unlicensed frequency of interest (ie, the SCell at the CA, or the cell operated by SeNB at the time of DC) may use different Radio Access Technology (RAT). For example, the licensed frequency cell may be an LTE (E-UTRAN) cell and the non-licensed frequency cell may be a UMTS (UTRAN) cell.

Furthermore, the above-described embodiment is merely an example relating to the application of the technical idea obtained by the inventor of the present invention. That is, the technical idea is not limited to the above-described embodiment, and it goes without saying that various changes can be made.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2014-186949 filed on September 12, 2014, and incorporates all of its disclosures herein.

1, 6, 7 Wireless base stations 3, 8 Wireless terminals 4 Wireless LAN access points 5 Wireless LAN terminals 101, 301 Transceivers 102, 302 Controllers

Claims (8)

It is the first radio station that operates the first cell of the licensed frequency and operates as a master node when the radio terminal implements dual connectivity.
A wireless communication means for communicating with the wireless terminal that executes carrier aggregation using a licensed frequency and a shared frequency, and
A control means for transmitting a measurement configuration including control information associated with a reference signal measurement in a cell operated at the shared frequency to the wireless terminal in the first cell, and a control means.
With
The control information includes information indicating the periodicity at which the first period in which the reference signal measurement is performed occurs, and an offset value for indicating the subframe number at which the first period starts.
The control means receives the result of the reference signal measurement executed in the first period based on the offset value and the information indicating the periodicity from the wireless terminal in the first cell.
The first radio station. The first radio station of claim 1, wherein the control information includes a Physical Downlink Control Channel that includes a Cyclic Redundancy Check (CRC) part scrambled by an Unlicensed Radio Network Temporary Identifier (U-RNTI). The first radio according to claim 2, wherein the U-RNTI is set to a common value for a plurality of wireless terminals that are in a wireless connection state at the license frequency and have the ability to communicate at the shared frequency. Station. The control information is set in common to a plurality of wireless terminals that are in a wireless connection state in the first cell and have the ability to communicate at the shared frequency, according to any one of claims 1 to 3. The first radio station listed. Prior to transmitting the Measurement configuration, the control means further receives a detection result of proximity to the second cell operated at the shared frequency from the wireless terminal, and obtains the detection result of the proximity to the detection result of the proximity. The first radio station according to any one of claims 1 to 4, which determines transmission of the Measurement configuration to the radio terminal based on the above. It is a method performed in the first radio station that operates the first cell of the licensed frequency and operates as a master node when the radio terminal implements dual connectivity.
Controls associated with communicating with a radio terminal performing carrier aggregation using the licensed and shared frequencies in the first cell of the licensed frequency and measuring the reference signal in the second cell operating at the shared frequency. It comprises transmitting a Measurement configuration containing information to the wireless terminal in the first cell.
The control information includes information indicating the periodicity at which the first period in which the reference signal measurement is performed occurs, and an offset value for indicating the subframe number at which the first period starts.
Further comprising receiving the result of the reference signal measurement performed during the first period based on the offset value and the information indicating the periodicity from the wireless terminal in the first cell.
Method. A method performed in a wireless terminal that performs carrier aggregation using a licensed frequency and a shared frequency.
Associated with communicating in the first cell of the licensed frequency with the first radio station acting as the master node when the radio terminal performs dual connectivity, and measuring the reference signal in the second cell of the shared frequency. The measurement configuration including the obtained control information is received from the first radio station in the first cell.
The control information includes information indicating the periodicity at which the first period in which the reference signal measurement is performed occurs, and an offset value for indicating the subframe number at which the first period starts.
The reference signal measurement is performed during the first period based on the offset value and the information indicating the periodicity, and the result of the reference signal measurement is obtained in the first cell of the first radio station. To further prepare for sending to,
Method. A wireless terminal that performs carrier aggregation using licensed frequencies and shared frequencies.
A wireless communication means for communicating with a first radio station that operates as a master node when the wireless terminal implements dual connectivity in the first cell of the licensed frequency.
A control means for receiving a measurement configuration including control information associated with a reference signal measurement in the second cell of the shared frequency from the first radio station in the first cell.
The control information includes information indicating the periodicity at which the first period in which the reference signal measurement is performed occurs, and an offset value for indicating the subframe number at which the first period starts.
The control means executes the reference signal measurement in the first period based on the offset value and the information indicating the periodicity, and the result of the reference signal measurement is obtained in the first cell in the first cell. Send to the radio station,
Wireless terminal.

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